Electrocochleography in cochlear implantation: Development,applications, and future directions

Electrocochleography (ECochG) is an electrophysiological technique that records electrical potentials generated by different components of the inner ear and peripheral cochlear nerve in response to acoustic stimulation. ECochG responses can be analyzed into (1) cochlear microphonics (CM), (2) auditory nerve neurophonics, (3) summating potential, and (4) compound action potential. Over the past few decades, there have been ongoing refinements in technique and updates in the understanding of recorded potentials. Historically, ECochG found its main application in the diagnostic evaluation of Meniere’s disease (MD). However, in the last decade, the focus has shifted towards cochlear implantation (CI). In patients with residual hearing after CI, combined electric and acoustic stimulation has resulted in improved hearing and speech outcomes. Despite efforts to mitigate trauma during electrode insertion, hearing preservation rates vary after surgery. During implantation, real-time ECochG offers an opportunity to measure frequency specific CMs elicited from a localized region in the cochlea as the surgeon inserts the electrode array. In extracochlear ECochG recordings, the recording electrode can be placed on the promontory, the stapes, or the tympanic membrane. Intracochlear ECochG can be performed by inserting a recording electrode into the cochlea or by using one of the CI electrodes as the recording electrode. The loss of intraoperative ECochG signal may indicate cochlear trauma from electrode insertion, but the association between intraoperative ECochG changes and cochlear trauma remains controversial. The ability to monitor cochlear trauma during CI electrode placement holds promise to improve hearing preservation outcomes, modify surgical techniques, and change electrode design. The goal of this review is to provide a comprehensive overview of the electrophysiology and history of ECochG, discuss its recent applications in CI, and explore the ongoing research in this expanding field.     

Development of auditory skills after cochlear implantation in children with inner ear malformations

Conclusions: CI improves hearing thresholds and auditory skills in children with most types of inner ear malformations. However, the development of sound detection skills is not as good as it is in children without inner ear malformations. Objectives: To investigate the influence of inner ear malformations on development of auditory skills after cochlear implantation (CI). Methods: Records of 20 children with inner ear malformations who underwent cochlear implantation before 4 years of age and followed up for more than 2 years were retrospectively reviewed. Hearing thresholds, the Meaningful Auditory Integration Scale (MAIS), and Meaningful Use of Speech Scale (MUSS) scores before and after CI were analyzed and compared with 20 age-matched deaf children who underwent CI. Results: The children with inner ear malformations showed significant improvements in hearing thresholds and the MAIS and MUSS scores 1 year after CI (p?p?p?相似文献   

Rare case of bilateral aural atresia and cochlear dysplasia: when cochlear implantation is not the answer

Objective and importance: Reports of patients with concurrent middle and inner ear anomalies are rare. These patients present a surgical challenge for cochlear implantation. The surgical risk must be weighed against the predicted benefit of the patient’s hearing outcome and subsequent development of speech and language as well as their quality of life.

Clinical presentation: Thirteen-year-old boy presented to the Otology clinic for auditory rehabilitation options. He has mild developmental delay, is non-verbal and communicates via American Sign Language. He was born with bilateral aural atresia and never wore amplification. On exam he has grade 1 microtia and complete ear canal atresia bilaterally. His behavioural hearing test shows profound sensorineural hearing loss of both ears. The computed tomography scan shows bilateral underdeveloped and completely opacified mastoid and middle ear, complete bony atresia of the ear canals, and an under-partitioned cochlea with poorly defined modiolus, among other abnormalities. The patient and his family were counselled on the available options as well as the need for any further studies.

Intervention: Counselling of patient and family.

Conclusion: While there have been reports in the literature of performing cochlear implantations in patients with a concurrent atresia and cochlear dysplasia, these were patients whose degree of inner ear anomalies was relatively minor and their prognosis of a good audiological outcome was favourable. The presented case is that of a patient for whom the surgical approach to the cochlea alone would be difficult. More importantly, his quality of life would not significantly improve in light of the predicted limited hearing and language development outcomes, given the severity of his inner ear abnormalities, limited communication abilities, prolonged period of deafness and developmental delays.     

Follow-up of cochlear implant use in patients who developed bacterial meningitis following cochlear implantation

Objectives/Hypothesis: The present study is a long‐term follow‐up of speech perception outcomes and cochlear implant use in three cases of meningitis that occurred after cochlear implantation. Study Design: Case series study. Methods: Study was performed on three children implanted with different models of Clarion® devices, two of them with positioner. Recognition and comprehension were assessed via the Italian adaptation of GASP (TAP) test, and phonetically balanced bi‐syllabic words in open‐set. High resolution computed tomography scan acquisition was performed to obtain axial coronal and oblique multiplanar reconstructions of the cochlea. Results: Two patients were affected by enlarged cochlear acqueduct and Mondini malformation the first carrying positioner. One patient had a normal cochlea, and the positioner could have been the main cause of bacterial spread. As a consequence of meningitis the child with normal cochlea and the other with enlarged vestibular acqueduct developed cochlear ossification, increased M‐level and worsening of hearing outcomes. The child with Mondini malformation developed facial nerve stimulation. Contralateral implantation was performed in the first two patients. Conclusion: Bacterial meningitis occurring after cochlear implantation may induce cochlear ossification, facial nerve stimulation, and permanent or temporary loss of implant use. Planned follow‐up with high resolution computed tomography and evaluation of M‐levels could be useful prognostic tools in the management of these patients.     

多导人工耳蜗植入后电极阻抗的初步研究

目的研究多导人工耳蜗植入后电极阻抗变化的特点,对比直电极和弯电极的阻抗差异,为人工耳蜗植入术后的调试提供参考。方法在Nucleus多导人工耳蜗编程调试界面上,应用R126V1.3和NRTV3.0软件,测试11例语前聋儿童在不同时期的阻抗值,并进行分析比较。结果CI24M和CI24Rcontour两种植入体阻抗随时间变化的基本规律是:术中较低,开机时最高,以后随时间推移逐渐降低。CI24Rcontour阻抗高于CI24M。结论人工耳蜗植入体阻抗开机后随时间推移而逐渐降低,新型CI24Rcontour植入体与CI24M相比,其阻抗值在术中至开机后3周内明显要高。     

Audiological performance after cochlear implantation: a 2-year follow-up in children with inner ear malformations

Conclusions: Open-set speech perception in children with an inner ear malformation is equal to that of other congenitally deaf children after an average of 2 years follow-up. Objective: To analyze audiological performance after cochlear implantation in a sample of children with radiographically detectable malformations of the inner ear compared to performance in prelingually deafened children at large. Materials and methods: Nine children with osseous inner ear malformations were compared to 22 congenitally deaf children, all of whom underwent cochlear implantation. All subjects were tested on their electrical evoked compound action potential. Speech perception tests were performed using the monosyllabic trochee polysyllabic test without visual support and the open-set monosyllabic wordlist. Results: In all, 20% of the congenitally deaf children in our center study have inner ear abnormalities. Inner ear malformations were limited to incomplete partition of the cochlea; none of the subjects had common cavity malformations. Electrical compound action potentials were successfully recorded in both groups intraoperatively. Speech perception tests on open-set speech yielded an average of 48.8% (SD 21.2%) in the group of children with inner ear malformations vs 54.5% (SD 21.1%) in congenitally deaf children. In four of nine cases with an inner ear malformation we encountered a minor CSF leak.     

Usefulness of radiological findings for predicting cochlear implantation outcomes in children with cochlear nerve deficiency: a pilot study

Conclusion: Children with CND received limited benefits from CIs and their results varied. The size of the vestibulocochlear nerve relative to the facial nerve could potentially be used as a predicator for CI outcomes in children with CND.

Objective: This study aimed to (1) retrospectively review the outcomes of cochlear implants (CIs) in children with cochlear nerve deficiency (CND) and (2) evaluate the clinical usefulness of radiological findings as predictors for post-implantation outcomes.

Methods: Study participants included 10 children with bilateral CND and profound sensorineural hearing loss. The preoperative magnetic resonance imaging and temporal bone computed tomography scans were evaluated. Auditory processing capability and speech perception performance were measured with Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scales. Aided hearing thresholds with CI were measured. The relationships between CI outcomes and the sizes of vestibulocochlear nerve and cochlear nerve canal (CNC) were analysed.

Results: Although post-operative CAP scores and hearing thresholds significantly improved in children with CND, their results were worse than those measured in implanted children with normal cochlear nerve. No significant correlation was found between the CI outcomes and the vestibulocochlear nerve diameters or the CNC diameters in children with CND. However, children with larger vestibulocochlear-nerve-to-facial-nerve-ratios got better results.     

Contemporary surgical issues in paediatric cochlear implantation

Abstract

Objective: To review the contemporary surgical issues in paediatric cochlear implantation (CI) based on published evidence. Design: Narrative literature review. Results: Surgical challenges in paediatric CI are discussed, with respect to post meningitic labyrinthitis ossificans; cochlear malformation; cochlear implantation in infants; auditory neuropathy and cochlear nerve deficiency; bilateral cochlear implantation; hearing preservation; otitis media; and device failure. Conclusion: Early CI is recommended if bacterial meningitis causes profound sensorineural hearing loss (SNHL). CI in cochleovestibular malformation requires pre-operative imaging to plan surgical technique, choice of electrode, and to anticipate complication. Children with congenital severe to profound SNHL should undergo early bilateral simultaneous implantation, preferably before 12 months of age, except those with auditory neuropathy spectrum disorder who should be implanted after one year. Soft surgical technique should be deployed in an attempt to preserve any residual hearing. Otitis media with effusion is not a contraindication to cochlear implantation, but active or recurrent acute otitis media requires resolution of infection with grommet insertion pre-operatively. Device failure in CI recipients requires a stepwise audiological, medical, radiological, and device integrity assessment to determine the need for reimplantation.     

Conservation of low-frequency hearing in cochlear implantation

Objective As results with cochlear implants have continued to improve, patients with some remaining cochlear function have become eligible for cochlear implantation. Thus, preservation of acoustic hearing after implantation has gained importance. Hearing preservation can be considered a benchmark for atraumatic implantation preventing neural degeneration from loss of residual hair cells or subsequent to local trauma. In this prospective study, the possibility of preserving low-frequency hearing in cochlear implantation using a modified surgical technique has been explored.

Materials and Methods In a prospective study design, 14 subjects with considerable low-frequency hearing of 2–60 dB in the frequency range 125–500 Hz but with unsatisfactory speech understanding with hearing aids of < 35% monosyllabic word understanding were implanted with a MED-EL COMBI-40+ cochlear implant. The insertion depth was intentionally limited to 19–24 mm to prevent damage to low-frequency regions of the cochlea. Pre- and postoperative pure-tone thresholds were measured.

Results Hearing was conserved within 0-10 dB in 9/14 subjects and within 11–20 dB in 3/14; in 2/14 subjects hearing was completely lost in the implanted ear. Thus hearing could at least partially be conserved in 12/14 subjects (86%). Median threshold values decreased by 10, 15, 17.5 and 5 dB at 125, 250, 500 and 1000 Hz, respectively. Even high levels of hearing, e.g. 30 dB at 500 Hz, could be maintained after implantation in some subjects.

Conclusions This study reports successful conservation of hearing after cochlear implantation using a modified surgical technique. Even high levels of hearing could be maintained, showing that implantation of an intracochlear electrode can be performed atraumatically with preservation of functional structures.     

人工耳蜗植入术后改良耳蜗位平片的探讨

目的 探讨改良后耳蜗位平片摄影位的临床应用价值。方法 21例人工耳蜗植入术后患儿(年龄30d～4岁)分别摄许氏提倡的耳蜗位平片摄影位和我们改良后的许氏耳蜗位平片摄影位,用Cohen(c)方法测出蜗管内电极数,将术中得数与2种片所得共3组数据行统计处理t检验。结果 2种平片均能清晰地显示蜗管内电极的位置和形态,2组X片结果与手术结果基本吻合,3组数据比较差异无统计学意义。结论 改良后耳蜗位平片摄影位方法简便,易使4岁以下患儿接受,且能满足了解人工耳蜗植入术后精确状态的需要。     

Dynamic visual acuity using “far” and “near” targets

Objective To investigate the auditory rehabilitative results achieved in five patients with cochlear implants (CIs) who subsequently received, due to poor results, auditory brainstem implants (ABIs).

Material and Methods Between April 1997 and March 2003, 37 patients (age range 14 months to 70 years) were fitted with ABIs in our ENT Department. Fourteen subjects had neurofibromatosis type 2 and 23 were non-tumor patients who had cochlea or cochlear nerve disease. Five subjects had previously been treated with a CI and received an ABI owing to the poor results achieved. One child had bilateral undiagnosed cochlear nerve aplasia and one was suffering from auditory neuropathy; three adults had total cochlear ossification.

Results The open-set sentence recognition score (auditory-only mode) 6–8 months after ABI activation ranged from 0% to 100% in adults. In 1 subject the speech-tracking score was 56 words/min with the ABI. The two children who had achieved no hearing ability with their CI were able to detect sounds and words as early as 3 months after activation of the ABI.

Conclusion CI failure as a result of anatomical abnormalities can be remedied by an ABI.     

听神经病及蜗神经发育不良儿童人工耳蜗植入的有效性

目的 通过问卷量表评估,探讨听神经病及蜗神经发育不良儿童的人工耳蜗植入效果.方法 实验组为2004年1月至2010年10月期间接受人工耳蜗植入的符合听神经病或蜗神经发育不良诊断标准、且术前至少佩戴3个月助听器并接受语言训练的患儿,共21例,其中听神经病9例,蜗神经发育不良12例.植入对照组为20例同期植入人工耳蜗的感音神经性聋患儿.所有人工耳蜗植入患儿均开机使用6个月以上.正常听力对照组为42例听力正常的儿童,按年龄分为正常听力A组(年龄在24个月以下)18例、正常听力B组(年龄24～ 48个月)16例和正常听力C组(年龄在48个月以上)8例.采用听觉行为分级(Categories of Auditory Performance,CAP)和言语可懂度分级(Speech Intelligibility Rating,SIR)两个量表进行评分,使用SPSS16.0软件对实验组得分与植入对照组和正常听力对照组进行比较.结果 听神经病组、蜗神经发育不良组、感音神经性聋组以及三组正常听力儿童的CAP得分(x±s,下同)分别为(4.44±1.50)分、(4.83±1.69)分、(4.55±1.66)分、(5.22±1.11)分、(6.75±0.45)分和(7.00±0.00)分,SIR得分分别为(2.66±1.11)分、(2.33±1.15)分,(2.40±0.75)分,(2.56±1.04)分、(4.12±0.81)分和(5.00±0.00)分.CAP和SIR得分在六组受试者间差异均具有统计学意义(x2=35.481,P＜0.001;x2 =40.549,P＜0.001);组内两两比较,听神经病组/蜗神经发育不良组与感音神经性聋组及正常听力A组得分比较,差异无统计学意义(P值均＞0.05),而与正常听力B组及C组相比,差异具有统计学意义(P值均＜0.01).结论 听神经病和蜗神经发育不良儿童接受人工耳蜗植入后,同感音神经性聋患儿一样,能够获得听觉及言语能力的进步,但落后于听力正常的同龄儿童.人工耳蜗提高此类患儿听觉及言语能力的远期效果还有待进一步随访和评估.     

3 T – MRI improves intrameatal cranial nerve detection in CI-candidates

Background: Cochlear implantation meanwhile is a well established standard therapy in different forms of hearing loss in most ages. Clear depiction of the cochleovestibular anatomy and the cochlear nerve are very important for indication and effectiveness of cochlear implantation.

Aim/objectives: Therefore the question raises whether Highfield MRI improves precision of preoperative diagnostic imaging especially along the the intrameatal portion of the vestibulocochlear nerve.

Methods: We analyzed the MRI scans of 216 temporal bones from 2007 until 2017. In all patients, CI was planned. We compared examinations using 1.5 and 3.0 T MR systems under the aspect of intracanalicular detection of the facial nerve, cochlear nerve, and the vestibular branches.

Results: 3?T-MRI was able to detect the cochlear nerve in all cases, a very important criterion for CI-indication. 3?T-MRI was also superior in the detection of facial nerve and especially the vestibular branches.

Conclusion and significance: The most effective preoperative examination of CI-candidates is the combination of 3?T MRI and multislice HR-CT of the temporal bone.     

先天性内耳畸形并中耳畸形患者多通道人工耳蜗植入术3例报告

目的：探讨先天性内耳畸形并中耳畸形患者行多通道人工耳蜗植入术的方法及效果。方法：1995年5月-2002年5月我院为3例罕见的先天性内耳畸形并中耳畸形患者经乳突进路行人工耳蜗植入术,分别植入27、28、32个电极,植入后3个月行声场测听。结果：3例患者均成功地行人工耳蜗植入,术中、术后无严重并发症发生,术后声场测听听阈达35-40dBHL。结论：罕见的先天性内耳畸形并中耳畸形患者也可行人工耳蜗植入术,术后效果满意。